What is this test?

Prothrombin time is a test used to check the amount of time needed for blood to clot. A prothrombin test is used to check any bleeding disorders. This test can also be used to check if the medicines given for blood clotting is working. This test is also called as an international normalized ratio (INR) which is a way of standardizing the results of prothrombin time test. This test is used to diagnose liver disease, vitamin K deficiency, hemophilia, leukemia, bone marrow disorders, problems with the immune system, Von Willebrand disease, and deficiency of clotting factors, etc.

Importance of Prothrombin Time test:

Blood clotting process is called coagulation, which stops bleeding. Clotting factors are needed for coagulation process which is a bunch of proteins. There are 12 clotting factors present in our body. Prothrombin time test is used to check five important clotting factors which are the factor I, II, V, VII, and X are working efficiently. Clotting factors are produced from the liver. Prothrombin is a type of clotting factor which gets converted to thrombin as soon as bleeding occurs. Prothrombin test measures the time taken for the conversion of prothrombin to thrombin to stop bleeding.

Why this test is performed?

This test may be recommended to you if you have a family history of bleeding disorders or if you experience symptoms like nosebleeds, gum bleeds, bleeding more often, bruising frequently, blood in stools, abnormal menstrual bleeding, swollen joints, joint aches, etc. This test is also recommended to you before having surgery. If you are on a blood-thinning medication like warfarin, heparin, enoxaparin, etc this test is recommended regularly to monitor the doses or to see if the therapy is working.


Some medicines may interfere with your test results, that are anticoagulants like heparin, warfarin, antiplatelets like aspirin, clopidogrel, factor Xa inhibitors like rivaroxaban, apixaban, fondaparinux, direct thrombin inhibitors like dabigatran, steroids like prednisolone, cortisone, hormones like estrogens and birth control pills, antacids like pantoprazole, ranitidine, etc. Some foods rich in vitamin K such as broccoli, soy, soybeans, chickpeas, kale, turnip greens, liver, etc make the prothrombin time faster than the normal.

Also known as PT Blood, PT test, Prothrombin Test, Prothrombin Time, International Normalized Ratio, INR.